Condensate pump



Nov. 27, 1962 J. D. BUCHANAN ETAL 3,065,712

CONDENSATE PUMP Filed Feb. 6, 1961 2 Sheets-Sheet 1 IIIIIIIIIIIIIIIIIIIIJOHN D. BUCHANAN KENNETH A. DARNE Y v INVENTORS Nov. 27, 1962 J. D.BUCHANAN ETAL 3,065,712

CONDENSATE PUMP Filed Feb. 6, 1961 2 Sheets-Sheet 2 FIG. 5.

EXHAUST q JOHN D. BUCHAxAIY H A. DAR E I NVENTORS United States Patent()fiice 3,i55,7l2 CONDENSATE PUMP John D. Buchanan, Tinionium, andKenneth A. Barney,

Raspeburg, Md, assignors to The Bendix Corporation, a corporation ofDelaware Filed Feb. 6, 1963., Ser. No. 87,470 6 Claims. ((11. 103-255)The present invention relates to a pump. More particularly, it relatesto a pump having electrodes immersible in a conductive liquid to causeheating and attendant increase in the vapor pressure of the liquid andthereby provide a force for pumping the liquid.

The pump of the present invention is especially suited for use withdehumidifiers and air conditioners of the refrigerating type. Themajority of dehumidifiers in use are provided with a simple drop pan orbucket for collecting the moisture condensed from the air. Thisarrangement is expedient since it provides for reduced cost ofmanufacture and permits flexibility in the choice of locating themachine. It is of considerable inconvenience to the user, however, sinceit necessitates daily or more frequent emptying of the condensate.Accordingly, it is an object of the present invention to provide asimple, reliable pump capable of elevating condensate through reasonabledistances.

Another object of the invention is to provide a pump which operatesautomatically upon the collection of a given volume of liquid.

A further object of the invention is to provide a pump requiring norotating parts for its operation, thereby improving its reliability andsimplifying its manufacture.

Still another object is to provide a condensate pump in whichreliability is further improved by the elimination of floats, switches,linkages, etc. from the controls.

Other objects and advantages will become apparent as an understanding ofthe invention is gained through study of the following description andthe accompanying drawings:

Briefly, the present invention comprises a pressure proof housingprovided with inlet and outlet valve means Within the housing are a pairof electrodes which upon immersion commence heating the condensate Asthe temperature within the housing increases, the inlet valve closes andthe internal pressure builds up At a certain pressure level the outletvalve opens and entrapped condensate is exhausted, the internal pressurebeing sufficient to elevate the liquid.

In the drawings:

FIGS. 1 and 2 are vertical sections of the present inventionillustrating, respectively, the appearance of the pump elements whilecondensate is being received but prior to operation of the pump, and theappearance of pump elements during operation of the pump;

FIG. 3 is a horizontal section of the invention illustrating theinternal elements in plan;

PEG. 4 is an elevation of the inlet valve for the pump illustrated inFIG. 1;

FIG. 5 is a vertical section of a pump similar to that of FIG. 1, butimproved in several respects;

FIG. 6 is a perspective of the inlet valve for the pump illustrated inFIG. 5; and

FIG. 7 is a pictorial representation of the use of the invention as anaccessory to a dehumidifier.

Referring to FIGS. l3, the pump includes a sealed housing 10 which maybe conveniently moulded in two pieces comprising a body shell 11 and acover plate 12. The joint 13 between the body shell 11 and cover plate12 is rabbeted to provide a snug fit and is sealed by means of screws 14and an adhesive or a suitable silicone-rubber compound applied uniformlyalong its length. The hous- 3,065,712 Patented Nov. 27., 1962 ingmaterial may satisfactorily be metal or plastic. If plastic is chosen,the material should be capable of withstanding moderate pressure atboiling water temperature without deterioration or deformation.

An inlet nipple 15 is moulded toward the top of one end of the housing10. Connected thereto is a flexible tube 16 conveying the liquid to bepumped. A vent hole 17 is positioned adjacent the nipple 15 to permitthe air displaced by entering liquid to escape. An outlet nipple 18,positioned beneath the inlet nipple 17, includes a check valve 19 in theform of a spring loaded ball. A flexible exhaust hose 21 is connecteddownstream of the check valve 19 to dispose the pumped liquid in a drainor elsewhere.

A temperature responsive inlet valve 22 is positioned within the housingIt) adjacent the apertures of inlet nipple l5 and air vent 17. Valve 22comprises a bimetallic strip 23, best seen in FIG. 3, secured to thehousing end wall by means of screws 24 driven into a projecting boss 25.A valve disk 26, provided with inner and outer O-ring seals 27 and 28,is flexibly secured to the free end of strip 23. Strip 23 is so arrangedthat increasing temperature bows the strip towards the housing end walland moves the valve disk into abutment therewith, thus sealing thehousing against loss of pressure through either the inlet or the ventapertures. FIGS. 1 and 2 illustrate alternative means of securing valvedisk 26 to strip 23.

FIG. 4 is the construction employed for the inlet valve of FIGS. 1 to 3,wherein the free end of strip 23 is pierced, as at 29, to receive a stem31 on valve disk 26. The stem 31 is then upset or peened to join thedisk to the strip. A pair of spaced semi-annular apertures 32 surroundaperture 29, leaving the filaments 33 as flexible supports for the disk26. In the preferred construction of FIG. 6, the free end of strip 23 isslotted and tabs 34 are bent back from the slot. Valve stem 31 is thenpivotally secured between the tabs 34 by means of a pin 35.

Again referring to FIGS. 1 and 2, a pair of horizontally extendingelectrodes 36 and 37 are supported within the housing it by means ofconductive straps 33 and 39 moulded into plate 112. A power cord, onlythe end of which appears at 41, connects straps 33 and 39 and electrodes36 and 37 to an electrical power source. The upper electrode 36 isplaniform and fits within, but does not contact, the cup-shaped lowerelectrode 37.

The lower electrode 37 is suspended above the bottom of the housing in asuflicient distance to provide a sump of substantial volume. Theentering condensate must first fill the sump volume of the housing priorto spilling over the upper lip 42 of electrode 37. When the condensatespills into the cup of electrode 37, a high resistance electrical pathis established and heating action commences. As the temperature withinthe housing rises, valve 22 closes and the internal pressure also beginsto increase. Finally, the boiling of the liquid Within the cup ofelectrode 37 increases the pressure sufficiently to force open the checkvalve 19 and pump the liquid out, elevating it through whatever head maybe present. Steam continues to exhaust through the check valve untilfinally the liquid in the cup of electrode 37 has boiled away. Therewill then be no conductive path between electrodes 36 and 37 and heatingceases. As the pump cools, its internal pressure drops and check valve19 closes. Further cooling produces a partial vacuum within the pumpcausing inlet valve 22 to open to permit the inrush of the condensatewhich will have collected in tube 16 during the pump discharge cycle.The generation of the partial vacuum as a result of the provision ofcheck valve 19 is a desirable feature since it forces the opening ofinlet valve 22 sooner than that valve would open reaces 712 '3 spondingsolely to the internal temperature of the housing. Thus the capacity ofthe pump is increased.

Several other features contribute to improved operation of the pump. Thecup-shaped electrode 3') retains liquid after the check valve 19 hasopened and the level of the liquid has dropped below the level of theelectrode. Steaming continues until cup 37 has boiled dry, thus insuringthat the pump will be completely emptied during an operating cycle. Itshould also be noted that the level of the lower edge of the bi-metalliostrip 23 is above the level of the upper lip of cup 37. This insuresthat the pump will commence heating before strip 23 becomes immersed.Otherwise, the liquid in the pump would act as a heat sink to strip 23'and the inlet valve would close later than is desirable.

The material from which electrodes 36 and 37 are constructed may bemetal or carbon. Nickel and stainless steel have been found satisfactorybut carbon is preferred both for its freedom from oxidation and for thefact that the resistance of the electrodes can be deliberately increasedby mixing other materials into the carbon. It is desirable that theelectrodes present a reasonable amount of resistance as a safetyfeature. The resistivity of dehumidifier condensate is considerablylower than that of pure distilled water due to the presence of dust andother atmospheric pollutants, say 20,000-40,000 ohms/in. cu. as comparedto 150,000 ohms/in. cu. Typical electrodes constructed of a lowresistance material draw from 2 to 3 amperes at 110 volts when suppliedwith dehumidifier condensate having a resistivity of about 20,0tlohms/in. cu. The addition of a slight amount of salt to the liquidreduces its resistivity to about 2,000 ohms/in. cu. and causes thecurrent to exceed 15 amperes. Greater amounts of salt can reduce theresistivity of the liquid to as low as l820 ohms/in. cu. and virtuallyshort circuit the pump. Since salt or other contaminants may beaccidentally or unwittingly introduced into the pump or liquid, acertain amount of electrode resistance may be provided top reventdangerously excessive current demands.

FIG. illustrates an embodiment of the invention improved in severalrespects over the structure of FIGS. 1-3. The inlet nipple is of anenlarged diameter permitting the use of larger diameter inlet tubing andeliminating the necessity for vent 17 of FIG. 1. The outlet nipple 18 ismoulded on the cover plate 12', rather than on the body shell permittingthe inlet tubing and outlet hose to be run generally in a straight line.Electrode 37' is riveted directly to cover plate 12' and electrode 36'is riveted to a boss 43 projecting from plate 12, thus eliminating theencapsulation of the conductive straps 38 and 39 and line cord 41 asshown in FIGS. 1 and 2. The connection of the line cord 4-1 toelectrodes 36 and 37 is not shown but simply comprises eyelets securedto the opposite ends of the electrode supporting rivets. An insulatingcover 4 guards against accidental contact with the exposed electroderivet heads and terminals of cord 41. A pressure relief plug 45 of thetype commonly encountered in pressure cookers is also provided. Plug 45is designed to blow out at a pressure well below that required to burstthe pump housing and thus protects against explosion of the pump, asmight occur if the outlet line became clogged.

FIG. 7 illustrates the use of the invention as an accessary to adehumidifier. Humid air is drawn past the cool evaporator coil 5% of theunit, whereupon droplets of moisture condense and drip down to acollecting trough 51. Trough 51 is moderately funnel-shaped, thusdirecting the condensate toward an outlet fitting 52. Space is normallyprovided in the unit housing to contain a drip pan or bucket. In thiscase, however, the inlet tube 16 of the pump of the present inventionhas been connected to the fitting 52.. When sufiicient condensate iscollected by the pump 19 to immerse its electrodes, heating commencesand the pump will operate as hereinbefore described to discharge thecondensate through the hose 21 in o a on e nt drain.

Several advantages of the pump are apparent from FIG. 7. Since there isno necessity to provide drop pan or bucket storage space, a pumpequipped dehumidifier can be made considerably more compact.Furthermore, the condensate is disposed of through a closed system,rather than remaining in an open pan whence moisture is fed back intothe air. 7

It will now be appreciated that the objects of the invention have beenrealized in a simple, automatically operating, reliable pump. Obviouslythe pump may be modified or varied in many respects without departingfrom the teachings of this disclosure. The invention is thereforelimited solely by the scope of the appended claims.

The invention claimed is:

l. A pump, comprising a closed pressure resistant housing, an inlet portfor admitting conductive liquid to said housing, said inlet port beingpositioned at an upper level of said housing, an outlet port throughwhich liquid may be exhausted from said housing, said outlet port beingat a lower level than said inlet port, a pair of spaced electrodeswithin said housing and positioned at a level intermediate of the levelsof said inlet and outlet ports, means supplying electrical power to saidelectrodes to cause heating upon immersion of said electrodes by liquidwithin said housing, and valve means for sealing said inlet port duringheating of liquid within said housing.

2. A pump, comprising a closed pressure resistant housing, an inlet portfor admitting conductive liquid to said housing, said inlet port beingpositioned at an upper level of said housing, an outlet port throughwhich liquid may be exhausted from said housing, said outlet port beingat a lower level than said inlet port, a pair of spaced electrodesextending horizontally within said housing at a level intermediate ofthe levels of said inlet and outlet ports, means supplying electricalpower to said electrodes to cause heating upon immersion of saidelectrodes by liquid within said housing, and a temperature responsivevalve for sealing said inlet port during heating of liquid within saidhousing.

3. A pump, comprising a closed pressure resistant housing, an inlet portfor admitting conductive liquid to said housing, said inlet port beingpositioned at an upper level of said housing an outlet port throughwhich liquid may be exhausted from said housing, said outlet port beingat a lower level than said inlet port, a first generally cupshapedelectrode disposed horizontally within said housing so as to receive andcontain a portion of the conductive liquid in said housing, said firstelectrode being positioned at a level intermediate the levels of saidinlet and outlet ports, a second electrode spaced from said firstelectrode and arranged to contact the liquid within the cup of saidfirst electrode, means supplying electrical power to said electrodes tocause heating so long as sufficient liquid is contained by the cup ofsaid first electrode to maintain contact between said electrodes, andvalve means for sealing said intake port during heating of liquid withinsaid housing.

4. A pump as claimed in claim 3 wherein said valve means comprises, incombination, a bimetallic strip fixed at one end and free at the otherend and a valve disk pivotally attached to the free end of said strip,said strip being positioned to move said valve disk into facingengagement with said inlet port as temperature increases within saidhousing.

5. A pump as claimed in claim 4 with additionally, a check valve forpreventing entry of liquid into said housing through said outlet port.

6. A condensate pump, comprising a closed pressure resistant housing, aninlet port through which condensate is admitted to said housing bygravity flow, a pair of separated electrodes in said housing including afirst generally cupshaped electrode arranged to receive and contain aportion of the condensate in said housing and a second electrodearranged to contact condensate Within the cup of said first electrode,means supplying electrical power to 5 said electrodes, an outlet portthrough which condensate References Cited in the file of this patent ispumped from said housing, said outlet port and said UNETED STATESPATENTS electrodes being so arranged that condensate entering saidhousing submerges said outlet port prior to contacting said 1,184,178 Bk May 231 1916 electrodes, and valve means for preventing the escape of5 1343,02? Rltcme Man 1932 steam through said inlet port whereby uponimmersion 2,015,672 Hanks 1, 1935 of said electrodes by condensateelectrical heating of the condensate commences and pressure resultingfrom steam- FOREIGN PATENTS ing of the condensate forces evacuation ofthe condensate 355,001 Germany June 19, 1922 through said outlet port.10 562,046 Germany Oct. 31, 1930

